35,202 reputation
53074
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location Vienna, Austria
age
visits member for 3 years, 4 months
seen 10 mins ago

If you have been following me around, you know that my main interests are general topology, set theory, and destroying users who post nothing but inane gibberish. The last is certainly not the least!


Projects I'd like to spend some time on:

  1. replace all occurrences of "Erdös" and "Erdos" by "Erdős"
  2. completely separate the and tags (i.e., empty this list).

32m
comment Questions about a real orthogonal $3 \times 3$ matrix
@JyrkiLahtonen: There is no need to remove the homework tag from questions. That will be automatically done in one week. See Tim Post's answer.
40m
comment A Hausdorff space which is not completely regular
Just because one particular continuous function doesn't separate a point from a closed set doesn't mean that none do. For example the continuous function $f : \mathbb{R}^+ \to [0,1]$ defined by $f(x) = \min \{ x , 1 \}$ will separate $0$ from the closed interval $[5,6]$. (Note, too, that any subspace of a completely regular space is itself completely regular; since $\mathbb{R}$ is completely regular, so, too, is $\mathbb{R}^+$.)
43m
comment A Hausdorff space which is not completely regular
Information about typesetting mathematics on this site can be found here.
43m
revised A Hausdorff space which is not completely regular
retitled; formatted improvement
1h
comment Range of Computation Function Problem
@NicholasKorman: Your old question is currently undergoing review by the community on whether it should be re-opened, though it is impossible to say how long this will take. However, it is strictly bad behaviour (and I know that you know this) to simply re-ask the same question. I feel that you have been making a concerted effort to try improve your question-asking. Please don't fall back on bad habits.
2h
revised The range of a function $f : n^+ \to \omega$ has a largest element.
retitled; retagged; Oxford comma seemed appropriate here.
2h
revised Generalizing a statement about direct limits in the category of $A$-modules to other categories
retitled
17h
answered Constructing semi-regular spaces
21h
revised Recursively enumerable language
edited tags
22h
revised Convergence/divergence of $\sum_{n=2}^{ \infty} [ (1+\frac{1}{\log n } )^{1/n}-1 ]$
me make better
22h
comment Comparing Variances
Since someone has taken the time to provide this question with an answer, it is only polite not to deface the question as you have done. Next time, please spend the necessary time to figure out exactly what you want to ask before you press the "Post Your Question" button.
22h
revised Comparing Variances
rolled back to a previous revision
1d
comment Solving a system of three linear equations with three unknowns
This is starting to look spammy.
1d
comment Why these two series are convergent or divergent?
For information about typesetting mathematics here, please refer to this page.
1d
revised All topologies on $X=\{ a,b \}$
phi is not the symbol for the empty set.
1d
revised Proving that a poset can be expressed as a union of subchains.
rolled back to a previous revision
1d
revised Counting combinations with a restriction of the form “either … or …, but not both”
retitled; aded tag; some minor body fixes
1d
revised Prototypical examples of functions in various function spaces
retitled
1d
comment A topology defined on collections of open covers of a topological $X$.
The discrete topology? The trivial topology? A topology induced by an arbitrary linear ordering of the open covers? You must make your question more specific. Are there properties that you are looking to reflect from $X$ into this new space? Why are you interested in this?
1d
comment A problem with an assumption in a previous lemma for the proof of Silver´s Theorem on SCH in Jech´s “Set Theory”
So, if I understand correctly (and correct me if I don't), you are basically asking the following: »Why in a proof of Lemma 8.15 (which only asserts that stationarily many $A_\alpha$ have cardinality at most $\aleph_{\alpha+1}$) does it suffice to assume that each $A_\alpha$ has cardinality at most $\aleph_{\alpha+1}$?«